Endosomal Phosphatidylinositol 3-Kinase Is Essential for Canonical GPCR Signaling
Yasunori Uchida1, Florentine U Rutaganira2, Damien Jullié2
1Department of Psychiatry (Y.U., D.J., and M.Z.), Department of Cellular and Molecular Pharmacology (F.U.R., K.M.S., and M.Z.), and Howard Hughes Medical Institute (F.U.R. and K.M.S.), University of California, San Francisco, San Francisco, California uchida@med.kobe-u.ac.jp mark.vonzastrow@ucsf.edu.
Abstract:
G protein-coupled receptors (GPCRs), the largest family of signaling receptors, are critically regulated by endosomal trafficking, suggesting that endosomes might provide new strategies for manipulating GPCR signaling. Here we test this hypothesis by focusing on class III phosphatidylinositol 3-kinase (Vps34), which is an essential regulator of endosomal trafficking. We verify that Vps34 is required for recycling of the β2-adrenoceptor (β2AR), a prototypical GPCR, and then investigate the effects of Vps34 inhibition on the canonical cAMP response elicited by β2AR activation. Vps34 inhibition impairs the ability of cells to recover this response after prolonged activation, which is in accord with the established role of recycling in GPCR resensitization. In addition, Vps34 inhibition also attenuates the short-term cAMP response, and its effect begins several minutes after initial agonist application. These results establish Vps34 as an essential determinant of both short-term and long-term canonical GPCR signaling, and support the potential utility of the endosomal system as a druggable target for signaling.
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